


What's a .

by SunWeaver



Series: Prompt Fills [1]
Category: Undertale (Video Game)
Genre: (nor Chara), Alternate Universe - Underfell, F/M, Female Reader, Fluff, Menstruation, Reader Is Not Frisk, Reader-Insert, Slice of Life
Language: English
Status: Completed
Published: 2017-07-02
Updated: 2017-07-02
Packaged: 2018-11-22 07:58:54
Rating: Mature
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 2,759
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/11375940
Author URL: https://archiveofourown.org/users/SunWeaver/pseuds/SunWeaver
Summary: Prompt: "UF!Sans comforting reader while she's on her [rough] period. Fluff ensues"





	What's a .

**Author's Note:**

> Prompt suggested by Prinxipesca !

Forget any plans for today, hell, forget any plans for this _week_. Monsters probably had it so much easier with how their reproduction is based solely on their magic, even the more mammalian ones. Though nope, humans were simply cursed to carry this horrible burden which has been titled " _a menstrual cycle_ ". Some folks don't have it all that bad, some have it to a rather terrifying degree, then there's _you_. You aren't being hospitalized for any chronic symptoms, but you're also not lucky enough to be spared terrible cramps and horrible moodiness.

 

Just the other night, you cried over having trouble deciding whether you wanted pizza delivered or take-out from down the street. Your boyfriend didn't want to see you cry anymore over the decision, so he went out and just got the take-out. In hindsight, you really wanted some pizza, but he helped make it up to you by getting you a chocolate bar while at it.

 

Oh, but he was in for a hell of a surprise, the two of you only recently moved into a kitschy little apartment together, and were learning quite a lot about each other now that you shared the same little home. Like his habit of changing clothes and dropping any articles on the floor, leaving them there "for later", and it was not just exclusive to the bedroom, the moment he'd get home, sometimes he'd just drop his coat by the door, not even mustering the effort to hang it up on the hooks that literally were no more than _2 feet from the front door_. Okay, you weren't a neat freak, but come on, really? You two probably had your _first couple's argument ever_ over him leaving socks just about everywhere and not bothering to pick any of them up. It was a bumpy start, but after you showed him how powerful your cold shoulder was when in bed and for about two days straight, he started to actually learn how to use a laundry hamper.

 

This past week though made you seem like you were slowly losing your sanity, not because of anything he did, but just that you were slipping into more depressive episodes, feeling anxious over minute problems, and becoming so easily irritable at everything:

 

The birds to sing outside were _dumb_ , the commercial breaks between television shows were _annoying_ , the way these cute heeled shoes of yours pinched your toes was _terrible_ , the fact that your boyfriend is a skeleton and yet _he snores when he lacks sinuses and lungs is **awful**_.

 

Last night, you had kicked him out of bed because of his chainsaw snores, not wanting to get into it with you at 2 in the morning, he simply took a blanket and grabbed his pillow to sleep out on the couch instead.

 

By morning, you learned the ugly truth as to why this was all happening.

 

First thing you come to find when you pulled down your underwear and sat down on the commode, was that horrible stain showing you have once again, started your _period_. This was partly just annoying in the aspect that you never much cared for it, why bleed out and be punished when you didn't get pregnant before marriage or whatever? It was so unfair. Birth control could perhaps help, but not like you are in much a financial state to get a hold of any, plus the headache of a process it takes to get started was too much time and effort you simply did not have. Nope. Instead, you'd just pop in a tampon and take some Pamprin and hope for the best.

 

Except here's the problem... You're down to two tampons and you're all out of Pamprin.

 

Okay, all hope is not lost though! Two tampons can last you... A day-maybe half a day... You have a pretty heavy flow and only now are catching it before you ruin anything more than your underwear, so changing tampons is kinda a given. Sometimes you do have to line your panties with a light pad given how quickly you can burn through these _cotton tube suckers_... Nasty, but true.

 

All you need to do is make a trip out to the drugstore, certainly not far where you live, about 2 blocks away. You already showered last night, so it'll just be a matter of getting dressed, grabbing your wallet and phone, then making the trip.

 

Of course, you're on your period, meaning that your stomach is in knots of feeling both bloated and hungry, you're even a bit nauseated, but nothing maybe a quick drink couldn't help to settle. You stroll out of the bathroom, still in your tank top and "Sweet Cheeks" shorts (your boyfriend bought it for you after the one nickname he uses on you from time to time, not to mention your butt looks popping in the little red shorts with white text across the back) as you pass through the living room and get to the kitchen. The TV is on as you can see the blanket cocoon on the couch have a bony arm sticking out from underneath and holding out the remote control to flip through the channels.

 

It just occurred to you that last night you kicked him out of bed over the fact that his snoring rivaled that of a car honking outside their window from time to time. And boy, did you feel guilty now as you allowed for your PMS mood swings to be lashed out on him. He committed no crime, other than just trying to sleep like any other reasonable being wishes to do. Yeah, you're certainly winning at being "Girlfriend of the Year".

 

"Sans?" you call to him, leaning through the kitchen bar to look out over to the stoic skeleton on the couch, "... Sans, good morning."

 

Only a grunt came as a reply.

 

Yeah, you fucked up. Going back to the fridge, you grabbed a bottle of water, cracking it open to take a few gulps. Suppose that while you're in here, maybe you could offer something to help repay him for being so rude last night. You return back to the bar and lean out, "Sansy, want me to make you some breakfast? I could make some bacon and eggs."

 

Momentarily, there was a bit of movement from under the blanket, as you could see the top of his skull and eye sockets peek out from the blanket, "... We got bacon?"

 

You couldn't hold back a smirk, just that innocently cute way he asked was something that made you love him all the more, "Mhm! How many eggs and pieces would you like?"

 

"Two eggs, four bacon."

 

"Can do." You had hoped to maybe go ahead and get dressed and be out the door so you could get the drugstore stop done and over with, but a quick breakfast could be a perfect little pick-me-up for the two of you.

 

* * *

 

 

"... I'm sorry about last night." you finally said, guiltily and letting your fork gently clink against your plate, "I was just... In a mood... You don't deserve that."

 

Sans was in mid-chew of his crispy piece of bacon, but then swallowed and gave a halfhearted attempt at a laugh, "Yeah, yeah, it's whatever. My brother used to always be in a mood, so it's no big deal."

 

"I just feel so bad," your propped your chin up on your hand, feeling all the downer over the situation the more you dwell on it, "I'm just really... Really sorry."

 

You heard him sigh through his nose and set the greasy piece of pork down, reaching out to instead hold your wrist, "C'mon now, sweet cheeks, no harm done, I'm already over it. So don't be so hard on your pretty little self."

 

That was easier said than done, but sure, you can try letting it go for now. Besides, you have to remember you're on your damn period, you only feel like garbage more now than any other time you aren't PMSing. And if he's telling this to you, then he's gotta mean it.

 

"Thank you..."

 

He grinned at you, only for his grin to quickly falter and his brows to knit with concern, "Whoa, hey, what's with the waterworks?"

 

Okay, it was way easier said than done, because here you are, about to start crying over your sunny side up eggs, "I-I just... Feel... _Awful_."

 

" _Whaaat?_ Awful for what? Come on, we got our moments, nothing to beat yourself up for." Sans reached up to rub the tears out of your eyes with his thumb, only for you to pull back and lean against your chair, "... Babe, what's the fuck is going on?"

 

You didn't answer, if anything, the excuse was just a shitty one. Someone can only pull the _"I'm on my period"_ card so many times before it was just your ticket out of not being held accountable for your actions.

 

"... Ugh, you know what? Whatever. Keep it to yourself, I don't care." he then stood up from the table, chair screeching back, "Here I am, tryin' to be helpful and shit, but _guess what_ , sweet cheeks. _I can't read minds!_ "

 

A little harsh, but not like you were helping any, he took his plate and dumped whatever remained on it into the trash, going and putting his plate in the sink, before marching off to the bathroom to take a shower. Yeah, by this point you're just no longer in the running for that "Girlfriend of the Year" award.

 

* * *

 

 

Instead of getting properly dressed and going to the drugstore, you just decide to take up the open nest on the couch to curl up on and continue to feel sorry for yourself and remember why you're a piece of trash. It sucked that of all the things to couple with a nasty menstrual cycle, would be how much depression would kick your ass. Staying curled up on the couch, your stomach knotted and ached, which seemed like a cruel punishment since just before eating you were pretty hungry. Now you were feeling sicker than when you just woke up. Anxiety over making Sans angry didn't help, not one bit.

 

You just lied there... 5 minutes... 10 minutes... Half an hour... Not moving and staring blankly at the TV.

 

Soon enough, Sans did reemerge, coming up in some ever stylish sweatpants and raggedy old t-shirt with a couple holes in it. He spots you on the couch and takes a moment to look you over. His socked footsteps make their way to your side, where he then crouches down to your level and blocks your view of the TV.

 

"Babe... What's up."

 

You don't speak up.

 

"... Babe, come on."

 

He was now getting persistent, reaching up to run his fingers through your hair and hold the back of your head, leaning in to "kiss" you on the forehead with his teeth.

 

"Seriously, you can talk to me."

 

You finally speak up, only muttering a single word.

 

"Come again?"

 

" _...my period..._ "

 

Now he gave you an especially puzzled face, "... Your... _Pyramid_...?"

 

"No, no." you give a tired sigh, you're fed up more with your own antics rather than him, "My period, I'm on my period and I've been PMSing for the past week, which is why I've been such a mondo bitch. And it's dumb, but it's honestly the worst cause now I'm in a lot of pain and I only have one tampon left and I'm out of Pamprin and I've been meaning to go down to the drugstore, but then I messed everything up between us, and-and--"

 

"Whoa whoa, slow down, slow down!" through your steadily accelerating rant, Sans looked like he was left in the dust and tried scanning your face for some answers, when not finding any, he spoke up, "Okay, uh, let's... Take this back a minute... First off... What the fuck is a _"period"_?"

 

 _.... Oh my god.... He doesn't know..._ For as long as you two have been dating, and for as long as he's been on the surface surrounded by humans with monsters integrating back into society... He's never, in his life or in the short time of being on the surface now, heard or learned about a "period" outside the context of a punctuation mark that ends sentences.

 

"... U-um..." god, where do you _start_? "It's... Where... Y...ou... Er... Where humans who... Have um... _Uteruses_.... Or... Um..."

 

"... Oh my god, wait no, you don't mean." Sans now had a wash of mortification over his face, making you grow concerned too, "... Do you mean that... Like... Am... Am I going to be a _dad?_ "

 

_.... Oh... my god...._

 

" _S-sugar! S-sweet chee-baby-BABE, I-I uh... I didn't-I didn't think we coul-no like, I didn't-or did-how--_ "

 

"Sans! Sans!" You were quick to wrangle him back in without getting too ahead of himself, "That's called "pregnant", I'm not _pregnant!_ If anything, a period means I'm not pregnant at all."

 

Sans blinked a moment, trying to comprehend what the hell that meant, "... What the _HELL_ does THAT mean?"

 

"Okay, okay! Just... Bear with me..." you took the next couple minutes to explain in loose detail about how menstrual cycles worked, and why they were needed, and just about any other little tidbits of information you could recall learning about them by way of brief sex ed classes in school and online research out of your own curiosity. Explaining all this only made Sans have a face of disgust, which... You expected since he comes from a line of monsters that never have to deal with menstruation unlike how humans do.

 

"Holy f..." he barely whispered out as you finished, "Babe... That sounds HORRIBLE!"

 

You were about to agree... Except that the reaction was kinda not what you expected to hear. Maybe you would have thought him to be more disgusted by the explanation and be revolted, but no he... Had sympathy for you.

 

"Man, humans really are tough, I mean, ya'll bleed when your hurt, and now you're telling me you bleed for the sake of bleeding?? Damn, if I was in your position, I think I'd be pretty pissy about a lot of things too." he got up to his feet, "Alright, what are you needin'? I'll go run down to the drugstore and get it for you."

 

"What?? You don't have to do that, honestly, I can get it myself, just some tampons and Pamprin--"

 

"Alright, I'm on it."

 

"Wh-Sans! Wait!"

 

You try to catch him, but the moment he turns a corner, he vanished. Him and his "shortcuts". Yeah, still were getting used to those.

 

If anything, you worried more now about him not getting the right brand or be hopefully lost and confused in the search for the elusive toiletries that were often kept nestled away somewhere far in the back of the store. You hurried to the bedroom to grab your phone, shooting him a text. He admitted that he was pretty clueless on where to look, so it was a good thing you texted him.

 

Honestly, you never expected to date a guy who would so willingly and go out of his way to go out to buy you tampons. Most men would just be too prideful to ever wanna be caught dead buying a box of tampons for their partners, yet I guess with Sans not even knowing of that taboo, it was just as casual as going out to buy you a soda.

 

Texting back and forth some more, and sending him a picture of the brand you most prefer, he was successful in the venture and suddenly re-entered into the bedroom with a bag in hand.

 

"For you, sweet cheeks." he cheekily grinned those sharp teeth of his, and you politely accepted the bag.

 

As you turned to go to the bathroom and store the box under the sink and the bottle of pills up in the medicine cabinet, you got roped into an embrace from behind, his arms hugged around your stomach, and he pressed his head to your shoulder, giving you small kisses to your back. This felt incredibly nice...

 

"I love you." he whispers to your ear, kissing up at your cheek.

 

You sway a little in his arms, leaning back against his body and enjoying this affection you received, "Hm, thank you." you say, giving him a kiss back on his cheek.

 

"So, how's about we make today a lazy day and just watch TV in our underwear on the couch, while cuddlin'."

 

"Sounds perfect."

 

**Author's Note:**

> You can suggest a prompt by commenting here! http://archiveofourown.org/works/11325570


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